On Wednesday, June 5, 2013, the South West Monsoon was set to leap northward on the Indian Subcontinent by the middle of the month.
By about June 12, the leading edge of the Monsoon was potentially slated to reach a line from Gujarat state to Himachal Pradesh state in northwestern India, based upon weather forecast tools available to AccuWeather.com. This could imply Monsoon onset in nearly all of India along with all of Bangladesh and Nepal.
As the Indian Monsoon strengthens and builds northward, characteristic outbursts of heavy to excessive rain were forecast to take place, especially along the west coast of India.
Beyond the middle of next week, early indications were that the leading edge of the Monsoon could, by about June 20, reach well into Pakistan, where Monsoon onset typically holds off until July.
As of June 5, Summer Monsoon onset had been declared in roughly the southern half of peninsular India, the India Meteorological Department (IMD) said. The leading edge of northward advance lay near Machilipatnam, Hyderabad and Ratnagiri, or roughly along the historical average line of onset, the IMD website showed.
The Indian (South West) Monsoon was underway over the southern part of India and much of the Bay of Bengal as of June 5, 2013, the time of this infrared satellite image. Thunderstorm tops stretched over central and northeastern India ahead of the line of Monsoon advance. Shown dark on the image, much of Pakistan and nearby India was in the midst of a pre-monsoon heat wave. (IMD website)
Heat wave preceding the Monsoon over the northwestern Subcontinent had strengthened during the week. Wednesday, temperatures in Pakistan spiked to 49 degrees C (120 degrees F) at Sibi, and 48.5 degrees C (119 degrees F) at Jacobabad. Bikaner was hot spot in India, hitting 44.6 degrees C, or 116 degrees F.
Northward spread of the South West Monsoon was to trim the pre-Monsoon heat, if not break it indefinitely.
The plum rains are known as "meiyu" in China, the "baiyu" or "tsuyu" in Japan, and the "jangma" in the Koreas. The heart of the plum rain season stretches from early June to mid-July, with a tendency to shift south to north across the affected area.
In the wake of the mid-June cloudbursts, most of Pakistan to northwestern India last week saw a return to dry, hot weather typical of the weeks leading up to the Monsoon onset. It was as if the Monsoon withdrew to its "normal" position for the latter half of June.
The 38.5 degree C (101 degrees F) reading Tuesday in Ajaccio, Corsica, may have been tops in Europe.
Monsoon Onset was June 13th, 2013, in Delhi, almost two weeks earlier than average. The June 15th onset at Karachi and Islamabad was more like three week ahead of schedule.
In Pakistan, hit-or-miss downpours missed the Sindh capital, Karachi. One did hit Pad Idan, where it left 60 mm of rain Wednesday. This was more than 20 times greater than the normal June rainfall.
It is still possible that this scenario is over wrought as to the intensity and spread of rain in Pakistan and northwestern India. However, it is the hunch of the present forecaster that some very unusual weather is going to unfold in the Subcontinent during the next week!